/*
 * Copyright (C) 2012-2016 Markus Junginger, greenrobot (http://greenrobot.org)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.greenrobot.eventbus;

/**
 * Posts events in background.
 *
 * @author Markus
 */
class AsyncPoster implements Runnable, Poster {

  private final PendingPostQueue queue;
  private final EventBus eventBus;

  AsyncPoster(EventBus eventBus) {
    this.eventBus = eventBus;
    queue = new PendingPostQueue();
  }

  public void enqueue(Subscription subscription, Object event) {
    PendingPost pendingPost = PendingPost.obtainPendingPost(subscription, event);
    queue.enqueue(pendingPost);
    eventBus.getExecutorService().execute(this);
  }

  @Override
  public void run() {
    PendingPost pendingPost = queue.poll();
    if (pendingPost == null) {
      throw new IllegalStateException("No pending post available");
    }
    eventBus.invokeSubscriber(pendingPost);
  }
}
